1. Field of the Invention
The present invention pertains to a release system for a clutch assembly, comprising a release slide, which is or can be connected to a stored-energy element of the clutch assembly to execute the release movement, and at least one brake element, which can be moved along with the release slide during the execution of a release movement. The brake element can be brought into braking interaction with a counter-braking element, which is or can be brought into essentially nonrotatable connection with a clutch output shaft. The position of the minimum of one brake element can be shifted relative to the release slide at least for the purpose of compensating for the wear which occurs in the area of the clutch assembly.
2. Description of the Related Art
A release system is known from U.S. Pat. No. 4,099,604, in which a brake element is movably connected to a release slide, which can slide in the same direction as that in which a clutch rotational axis extends to execute release movements. When a release movement is executed and the clutch has been completely released, the release slide is moved even farther by appropriate actuation, and the brake element is thus pressed against a counter-braking element, connected nonrotatably to a clutch output shaft. As a result, a braking force is exerted on the clutch output shaft and thus on the transmission input shaft. This is advantageous especially when such systems are used in conjunction with unsynchronized transmissions. In order to ensure in an arrangement of this type that, even after the friction linings of the clutch assembly have become worn, the release system and also the brake system provided for the clutch output shaft will still have the same actuating characteristic or working characteristic, a wear compensating mechanism is provided, by means of which a relative displacement occurs between the release slide and the pressure plate upon the occurrence of wear without any change in the original installation position of the stored-energy element. This ensures that the release slide and thus also the braking element will always remain in approximately the same installation position regardless of the amount of wear and that the working characteristics of the braking arrangement for the clutch output shaft will always remain the same during the execution of clutch-release operations.
A release system for a clutch assembly is also known from U.S. Pat. No. 3,912,058, in which a release slide, which can be displaced by the introduction of hydraulic fluid so that it can execute release movements, can also be used to push a brake element to generate a braking force at least in the situation where the release stroke exceeds a certain value. To take into account the fact here, too, that, as wear occurs, the installation position of the stored-energy element and thus also the base of the release slide can change, the brake element or a part thereof and the release slide form a piston/cylinder unit. This unit has a cylinder chamber, into which fluid is introduced to an extent corresponding to the amount of wear and thus to the axial displacement of the release slide. The relative displacement between the release slide and the section of the braking element working together with the slide to form the piston/cylinder unit, which relative displacement occurs as a result of wear, is ultimately compensated by the increase in the volume of the fluid chamber and the filling of this fluid chamber with fluid. In spite of the displacement of the release slide occurring as a result of wear, therefore, the section of the brake element cooperating with it to form the piston/cylinder unit is held in the same axial installation position, so that, for all succeeding clutch-release operations, a uniform working characteristic can be obtained, at least in the area of the system which provides braking force for the clutch output shaft or transmission input shaft.
It is the object of the present invention to provide a release system for a clutch assembly which is of simple design and which nevertheless provides a uniform braking characteristic both in the area of the clutch assembly and in the area of the release system itself.
In the release system according to the invention, a latching arrangement includes latching teeth provided on one of the release slide and the brake element, and a latching element provided on the other of the release slide and the brake element. Upon the occurrence of wear, the latching arrangement allows relative movement to occur between the release slide and the brake element, whereas, upon the movement of the release slide in the release direction and the resulting braking interaction between the minimum of one brake element and the counter-brake element, the latching arrangement allows essentially no relative movement between the release slide and the brake element.
As a result of the present invention, a simple mechanical design is provided, in which ultimately the displacements occurring in the area of the clutch assemblyxe2x80x94regardless of whether they are caused by wear or manufacturing tolerancesxe2x80x94can be compensated easily in the area of the release system or in the part of the system in which the braking force is produced. There is no need to provide any hydraulic devices, as a result of which the arrangement according to the invention can be used especially for clutch systems in which no provisions are made for hydraulic actuation but in which, instead, mechanical actuation is transmitted by means of a Bowden cable or the like.
So that the release system according to the invention can be easily assembled, especially in conjunction with the performance of maintenance work on a vehicle containing one of these systems, it is proposed that the latching element be designed in the form of a latching ring, held on the one component or assembly with essentially no freedom to move in the release direction, which ring can be disengaged from the latching teeth by deforming it in a certain way such as by spreading it open.
A mechanically very simple but still sturdy and reliable design can also be achieved by providing the latching teeth on an outer circumferential area of the minimum of one brake element and by providing the latching element with a latching engagement area, which projects out over an inner circumferential surface of the release slide to engage with the latching teeth.
It is also possible, for example, for the latching ring to be held in an inside circumferential groove in the release slide.
So that the release system according to the invention will be able to adjust itself automatically in the area of the brake section, a motion-limiting device can be provided, which prevents the minimum of one brake element from moving more than a certain distance away from the counter-brake element.
It can be provided, for example, that the motion-limiting device comprises a retaining element, which is or can be attached to a stationary assembly, preferably to the transmission housing, which retaining element acts by way of at least one retaining section on the minimum of one brake element to limit its movement.
To ensure that, during the operation of the clutch in rotational mode, a suitable braking force can be exerted on the transmission input shaft, an antirotational locking system is preferably provided in the arrangement according to the invention, which prevents the minimum of one brake element from rotating.
A simple design requiring only a relatively small number of parts can be obtained by designing the antirotation lock in the form of at least one locking pin, which is provided on the minimum of one brake element. This pin is able to move in the release direction and can thus can engage in a locking recess in the retaining element.